The present invention relates to a cord material having reduced drag force when subjected to fluid flow. The cord material can be suitable for use in lined textile structures with a gliding component, such as kites. An embodiment of the invention comprises a plurality of braided or woven strands, in which at least one strand is different from the other strands in size, surface properties, or other characteristic affecting aerodynamic or hydrodynamic properties relating to the cord.
In loaded line systems, such as kites, the lines typically experience wide ranges in angle of attack and relative wind speed during normal usage. Line drag in these systems is considered parasitic drag, and can make up a sizeable portion of total wing drag, reportedly up to thirty percent for large wings with a high number of lines. At some critical angles of attack and airspeeds, lines can enter a vibration mode in which a given line drag has been shown to increase to about 250%. Line drag spikes or peaks, troughs or gullies, resulting from specific combinations of wind conditions can cause poor handling, inconsistent, and/or other than expected results from control inputs.